The University of California, San Francisco (UCSF) proposes a cooperative agreement to lead a node in the National Institute on Drug Abuse Treatment Clinical Trials Network (CTN). The overall goal of the Research Node is to participate in and conduct high-quality multi-site clinical trials of interventions for drug abuse and addiction and to guide the development, dissemination, and adoption of effective interventions in the field. Our Research Node will consist of a Regional Research and Training Center (PRTC) at UCSF that is linked in partnership with researchers at the University of Arizona and with community-based treatment programs (CTPs) in California and Arizona. Our California-Arizona Research Node will stimulate research to improve the effectiveness of treatment of addiction to opiates, cocaine and methamphetamine, nicotine, and other abused drugs. The gap between research and treatment is one of the most critical unresolved issues in drug abuse. The Node will foster collaboration among scientists and practitioners to stimulate new research improving the effectiveness of drug abuse treatment in community settings. The aims for the proposed Research Node are: (1) to participate in clinical trials of behavioral, pharmacological, and combined therapies for drug abuse and addiction; (2) to work with the national CTN leadership in development and implementation of research studies with special attention to patients with such co-occurring problems such as HIV, smoking, and hepatitis C; and to develop and maintain (3) an administrative infrastructure (4) a research infrastructure, and (5) a clinical infrastructure to accomplish these aims. The NIDA CTN can have a significant role in closing the gap between research and treatment in drug abuse. This Research Node has the potential to accelerate the advance of clinical trials and translational research over the coming decade.